Andrew Lansley has said that NHS services will still be free at the point of use – but which services will they be? Photograph: Max Nash/PA

Andrew Lansley and his colleagues assure us that under their plans to privatise the NHS, "services will still be free at the point of use". But they fail to add a key proviso: provided the services are still available. In reality, a growing list of services won't be available, and so won't be free.

Of course, some services that the NHS originally provided, such as long-term care for frail older people, have long been officially withdrawn; and others, like prescriptions and dentistry, are still provided but subject to charges. Under the health and social care bill there will be further contraction of what is provided free on the NHS. Local clinical commissioning groups, not the secretary of state, will decide what services it is "reasonable" to provide out of the budgets they are given, and the package will gradually contract.

This process has already begun under the pressure of the so-called productivity savings recommended by McKinsey. NHS services are being withdrawn in an unannounced, piecemeal and unaccountable way.

In 2006, Croydon primary care trust drew up a list of 34 procedures that would not be paid for in cases where they were judged ineffective or "cosmetic". But the list also included cataract surgery and hip and knee replacements, on the grounds that their benefits were minimal in "mild" cases. Obviously, what is considered a mild case is liable to be modified by financial pressures. By 2010, the Croydon list was being used widely by other PCTs as a means to save money. In some areas, one commentator noted, "only 'urgent' treatment – cancer, fractures and A&E – are funded, and all other procedures are either delayed or the patient is denied funding".

So a new postcode lottery for treatments has developed, largely unreported. NHS North Central London has a relatively short list of 36 treatments it won't pay for unless there are special circumstances. South West Essex has a list of 213. In effect, people who need these treatments have to pay for them privately and if they can't pay for them, they have to do without.

On top of this, GPs are being prevented from referring patients to specialists. In some areas indebted primary care trusts have simply limited each GP to a maximum of four referrals a week, regardless of how many patients need specialist attention. In other areas GP referrals are being intercepted by referral facilitation services (a name that might have been invented by Orwell himself), also called "referral gateways", run by private firms. One of the first was in west London, where the American health insurer UnitedHealth has a contract to override GPs' judgments and tell patients to have physiotherapy or use more painkillers instead of seeing a specialist.

A patient with good communication skills and determination may manage to overcome this obstacle. One west-London patient whose NHS surgeon had previously told her she needed a new knee, but who was denied it by UnitedHealth, had to pay over £1,000 and spend a year getting a scan and other surgeons' opinions to finally prove she needed it, and get back onto the NHS waiting list. But for many this is not possible. For them, free specialist services turn out not to be available.

Under the bill the range of what is available for free seems certain to contract further. Commissioning groups will have fixed budgets. The for-profit "support organisations" that are being lined up to do most of the commissioning for them will have a strong incentive to limit costs, and therefore the treatments to be paid for. CCGs also look likely to be free to decide that some treatments recommended by hospital specialists are "unreasonably" expensive, and refuse to pay for them, as health maintenance organisations do in the US.

A core of free NHS services will remain, but they will be of declining quality, because for-profit providers will cherry-pick the most profitable services. NHS hospitals will be left with the more costly work, so staffing levels and standards of care will be forced down and waiting times will get longer. To be sure of getting good healthcare people will increasingly take out private insurance, if they can afford it. At first most people will take out the cheaper insurance plans now on offer that cover just what is no longer free from the NHS, but gradually insurance for most forms of care will become normal. The poor will be left with a limited package of free services of lower quality.

What is available on the NHS should be determined nationally, in a transparent and democratic way, not by unelected local bodies. The bill will allow the secretary of state to deny responsibility when good, comprehensive, free care has become a thing of the past.